Telemetric system



Oct. 3, 1950 A. J. HORNFECK 2,524,665

mnmmxc sYs'rEu Filed Oct. 25, 1947 IN V EN TOR.

'1 Y IS ANTHONY J HORNFECK FIG. 2 (W Afro EY Patented Oct. 3, 1950 TELEMETRIC srs'rEM Anthony J. Hornfeck, Lyndhurst, Ohio, assignmto Bailey Meter Company, a corporation of Delaware Application October 25, 1947, Serial No. 782,114 Claims. (Cl. 318-29) This invention relates to telemetric systems, and more particularly tosystems for transmitting signals in response to a variable and positioning a receiving member by the signals at a remote point to provide an indication orrecord of the variable. I

- A preferred form of my invention may include a transmitting mechanism operating to produce a signal varying in response to a variable to be tioned in response to changes in the position of thetransmitting member.

The transmitting member 3 is shown herein pivoted at 6 and operatively connected to a device 1, such as a Bourdon tube, responsive to a variable condition, such as'the temperature or pressure within a conduit 8. The device I could as well be responsive to other variable conditions, such as the flow of fluid, changes in liquid level, etc. A scale 9 cooperates with the transmitting member to provide an indication of changes in the condition, and a pivoted contactor is operatively engaged by the member 3 to be positioned by the latter. A pivoted contactor |2 engages the periphery of a cam l4 and is arranged to be moved by the latter into engagement with the contactor The cam M has a substantially uniform rise and is rotated in the direction of the arrow at a time intervals for creating different unbalancing conditions. The unbalancing effect on the network is proportioal to the diiference between the products of the unbalancing conditions and the intervals of time during which each is applied. Means responsive to an unbalance of the network may be provided for rebalancing the latter and for positioning suitable indicating or recording means.

An object of my invention is to provide an improved teiemetric system. Another object is to provide a telemetric system having improved transmitting and receiving mechanisms. Yet another object is to provide a telemetric system which includes only a pair of wires between a transmitter and a receiver, and which operates to provide an indication or record at the receiver of a variable by the transmission of signals at low voltage over the pair of wires. Other objects will appear in the course of the following description.

In the accompanying drawing there are shown for purposes of illustration, two forms which my invention may assume in practice.

In this drawing:

Fig. 1. is a schematic diagram of a telemetric system' embodying my invention.

Fig. 2 is a schematic diagram of an improved transmitting mechanism adapted for use in the system of Fig. 1.

Fig. 3 is a schematic diagram of a receiver adapted for use with the transmitters of (Figs. 1 and 2.

Referring to the drawing, and more particularly to Fig. 1, it will be noted that there is shown a telemetric system including a. transmitter I and a receiver 2, the transmitter having a. movable transmitting member 3, and the receiver having a receiving member 4 which is arranged to be posiconstant speed by a motor l5. The contactors H and I2 are connected to conductors l1 and I8 leading to a source of alternating current, and connected in the circuit with the conductor |8 at the receiver is a relay winding l9 which controls the position of an armature 20. ,Contact arms 22 and 23 on the armature are engageable selec-' tively with contacts 24 and 25 for completing circuits through heating elements 21, 28 and conductors 30, 3| energized from a source of alternating current through a constant voltage regulator 32.

At the receiving end of the system is a balanceable bridge network having resistance element 34 and 35 forming one pair of its legs, and resistors 36 and 31 combined with portions of a potentiometer resistance 38 to form'the other pair of its A movable contact 40 engages the potenlegs. tiometer resistance and is operatively connected to a motor 4| to be positioned by the latter for balancing the bridge network. The receiving member 4 is also connected to the motor and is positioned by the latter relative to a scale 42 for indicating the value of the condition measured. Diametrically opposite points of the bridge are connected to a source of alternating current by conductors 44, 45. The movable contact 40 and a point on the bridge between the resistance elements 34, 35 are connected by conductors 46, 41 to an amplifier and control device 50 from which the motor 4| is energized. The motor 4| is shown herein as having opposed pole windings 5 l, 52am! a field winding 53 connected to a suitable source of alternating current. It the pole winding BI is short circuited the motor will rotate in one direction, and ii the winding 52 is short circuited the motor will rotate in the opposite direction. If both of the windings 5|, 52 are short circuited or open circuited, the motor will not rotate in either direction. The amplifier and motor control device may be like tat disclosed in the Ryder Patent 2,333,393 granted November 2, 1943, this asaaees device operating on an unbalance of the bridge in one direction to short circuit the pole winding i, and operating on an unbalance in the opposite direction to short' circuit the pole winding 52. The direction of rotation of'the motor is such as to move the contact 40 over the potentiometer resistance 3B in a direction to rebalance the bridge. The resistance elements 34, 35 are arranged so as to be heated by the elements 21, 28 respectively, and the resistance of the elements varies in proportion to'their changes in temperature.

With the parts in the positions shown in Fig. 1, a circuit is completed through the conductor 30,

i the contact arm 22, the heating element 21 and the conductor 3|. The element 21 then operates to heat the resistance element 34 and tends to produce an unbalance of the bridge. As soon as the cam is rotated from the position shown to a point where it moves contactor l2 into engagement with contactor II, the relay winding I9 is energized to move the contact arm 22 out of engagement with contact 24 and to move the contact arm 23 into engagement with the contact 25. The circuit through the heating element 21 is then broken, and the circuit through the element 28 is completed to effect a heating of the resistance element 35. If the contactor II is positioned by the transmitting member 3 so that the time intervals during which the contactors H and 12 are engaged and disengaged, are equal, then the resistance elements 34, 35 will be heated equal amounts during each revolution of the cam and their resistances will be substantially equal.

It is true that one of the resistance elements is cooling while the other is being heated, but the 'cam I4 is rotated at such a speed that the intervals of heating and cooling are comparatively short and the temperature changes during each interval are not suflicient to produce an unbalance of the system. If the condition changes so as to move the member 3 and position the contactor ll further from the contactor l2, the time intervals during which the contactors H and I2 are held closed are reduced while the in; tervals during which they are held open are correspondingly increased. The heating element 21 will then be energized during longer periods, and

' the element 28 will be energized during shorter periods. This will result in an increase in the temperature of the resistance element 34 and a decrease in the temperature of the resistance element 35. Theresistances of the elements will change in proportion to their changes in temperature and cause the bridge to become unbalanced. This will result in an energizing of the amplifier and motor control device so as to eflect operation of the motor to move contact 40 in a direction to rebalance the bridge. The receiving member 4 will be positioned at the same time by the motor 4! to indicate on the scale 42 the value of the condition at the transmitter. If the transmitting member 3 is moved to position the contactor ll nearer to the contactor l2, the time intervals during which the element 28 is energized are increased and the intervals during which the element 21 is energized are decreased. This results in an unbalance of the bridge in the opposite direction and an operation of the motor 4| to rebalance the system again.

In Fig. 2 I have shown another transmitter adapted for use in the system in place of the transmitter of Fig. 1. The transmitter 01' Fig. 2 includes transformers and 56 having primary windings 51 and 58 connected to a source of alternating current, and aiding secondary windings conductors, 65. A core member 61 is arranged between the primary and secondary windings oi the transformer 55 and is connected to one end or a pivoted member 58 which engages at its other end with a cam 69 rotated at a constant speed by a motor 10. The cam 69 is shaped so as to reciprocate the core member 81 at a constant speed between the windings of the transformer. Arranged between the primary and secondary windings of the transformer 58 is a core member 12 which is connected to a device 12, such as a Bourdon tube, responsive to some variable condition. Leading from the closed loop at points between the aiding secondary windings are conductors 14 and 15 connected to a relay 1! like that disclosed in my application, S. N. 633,891, filed December 8. 1945. This relay is of the electronic type and is operative at a very small voltage of a predetermined phase to move a contactor 14 into engagement with a contactor I! for completing the circuit through the conductors I1 and ii. The core member 12 may be considered as a transmitting member since the closing of contactor 18 to energize the conductors II, II is determined by the position assumed by this member.

When the core members 61 and 12 are in the same positions with respect to the windings of their transformers, the voltages induced in the corresponding secondary windings are equal and opposite so that the voltage across the conductors 14, 15 is zero. If the core members are displaced from each other in one direction, a voltage of a certain phase exists across the conductors 14, I5, and the value of the voltage varies with the amount of displacement. when the core members are displaced in the opposite direction, a voltage opposite in phase to the first voltage exists across the conductors 14, 15. The range of reciprocation or the core member 61 should be adjusted so that its upper and lower limits are equal to or greater than the limits of the core member 12 on maximum changes in the condition to be measured. The range of the core member 61 may be determined by the size of the cam 69 and the location of the pivotal support for the member 58.

Assume that the core members are in the same positions with respect to the windings of their transformers and that the core member 12 remains in this position while the core member 41 is reciprocated. A very slight movement of the core member in one direction will produce a voltage of a phase which operates the relay II to close the contactor 18 with the contact 19. While the core member moves in this direction to the end of its stroke and then returns to its initial position, the voltage will continue to be of a phase to operate the relay. As soon as the core member returns to its initial position the voltage across conductors 14, 15 becomes zero and the contactor 15 moves to its open position. A movement of the core member to the other side of its initial position results in a voltage opposite in phase to the first voltage, and the contactor 18 remains in its open position. It the core member 12 is in a position mid-way between the positions it would assume at the opposite limits of the condition measured, and if the core member 61 is reciprocated between corresponding limiting positions, the distances traveled by the core member 81 at opposite sides of the core 12 are equal and result in a holding oi the contactor 14 open and closed equal inter- J vais of time. A movement of the core member "from its mid-position means that the core member 81 mustmove an equal amount from such positioirto reach a point from which it may travel in either direction to produce volt-. ages of diiierent phase. Since the core member 81 will have a greater distance to travel in one direction t an the other from its new position, the contac I8 will beheld open or closed longer intervals of time. The resistance elements 88, 88 will then be heated unequal amounts and will cause the bridge to be unbalanced. The amplifier and control device III will be energized by the bridge unbalance-and eflect an operation of the motor II to position the contact 48 for rebalancing the bridge. The receiving member 4 will be positioned by the motor at the same time to indicate on the scale 42 the value of the condition measured,

In Fig. 3 I have shown another receiver similar to that connected in the system of Fig; l, but having a different arrangement for controlling the energizing oi the heating elements in response to signals received. The receiver includes the resistors 88, 88, 88, 81 and a potentiometer resistance 88 connected in a bridge circuit, as in i Fig. 1, and diagonally opposite points of the circuit are connected to the secondary winding of a transformer," which has its primary winding energized from a source of alternating current. The contact 48 for the potentiometer resistance is adjustable manually to vary the zero balance of the bridge, but is not moved after adjustment has been made. The amplifier and control device 88 is connected to the contact it and to a diagonally opposite point of the bridge for eil'ecting an operation of the motor ii, in one direction or the other in response to bridge unbalance. The heating elements 21 and 28 are-energized from secondary windings II and 84 of a transformer 88. The adjacent ends of the heating elements are connected by a common conductor 88 to the adjacent ends of the secondary windings 83, 84. The other end of the heating element 21 is connected by a conductor 81 and'a contactor 88 to the other end of the secondary winding 88, and the other end of the heating element 28 is connected by a conductor 88 to a movable contact 8! of a potentiometer connected across the secondary winding It. The contactor 88 is opened and closed in response to signals transmitted through the conductors l1 and II to the relay i 3 my copending divisional appIication B. N. 187,888 filed April 22, 1950.! I

What I claim as new and desire to United States Letters Patent is:

1. A telemetric system comprising, in combination, a movable transmitting member, a movable receiving memberremotely located from said transmitting member, means for positioning said transmitting member in response to changes in the magnitude of a variable, a balanceable bridge circuit adjacent said receiving member, resist ance elements forming legs of said bridge and varying in resistance in response to changes in temperature, an electric heating element for each of said resistance elements, means for intermittently energizing one of said heatingelements during time intervals dependent upon the posimas,

tions of said transmitting member, a reversible motor operatively connected to said receiving member for positioning the latter, means responsive to unbalance conditions of said bridge and operative on unbalance to en'ect an operation of said motor, and means operatively connected to said motor for rebalancing said bridge.

2. A telemetric system comprising, in combination, a movable transmitting member. a movable receiving member remotely located from said transmitting member, means for positioning said transmitting member in response to changes in the magnitude of a variable, a balanceable bridge circuit adjacent said receiving member, resistance elements forming legs of said bridge and varying in resistance in response to changes in temperature, electric heating elements for said resistance elements, means for energizing one of said heating elements during portions of fixed time intervals, said portions varying with the positions of said transmitting member, means for energizing another 01' said heating elements winding l8, and the contact 8| is positioned by I the motor 4| along the potentiometer.

It will be noted that the element 21 is subjected to the full voltage of the winding 88 during in tervals of time varying with the transmitted signals, and the element 28 is subjected continuously to a portion of the voltage across the winding II. If these'elements heat the resistances 8i and 88 equal amounts, the bridge circuits will be balanced. A change in the transmitted signal will result in a change in the heating of the resistance 84. The bridge will then be unbalanced and effect an operation of the motor to move the contact 8| and vary the heating of the resistance 88 until the bridge is rebalanced.

While there are disclosed in this application several forms which my invention may assume in practice it will be understood that it may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

Certain features of my invention, disclosed but not claimed herein, are disclosed and claimed in at least during the remainder of said time intervals, a reversible motor operativel connected to said receiving member for positioning the latter, means responsive to unbalanced conditions of said bridge and operative on unbalance to eifect an operation of said motor, and means operatively connected to saidmoto-r for rebalancing said bridge.

3. A telemetric system comprising, in combination, a transmitter including two transformers, each having a primary winding and a pair of aiding secondary windings, means for energizing said primary windings, means for connecting said secondary windings in a closed loop, core members movable between the primary and secondary windings of each of said transformers, means for reciprocating one of said core members in a predetermined path, means for positioning the other of said core members in response to changes in a variable to be measured, a phase sensitive relay connected to said closed loop at points between the secondary windings of each of said transformers, a circuit connected to a source of power and having a contactor controlled by said relay, 9. receiver including a balanceable bridge network, means operating when said circuit is energized to produce a condition tending to unbalance said bridge in one direction and operating when said circuit is deenergized to produce a condition tending to unbalance said bridge in the opposite direction, a reversible motor, means op.- erative on unbalance of said bridge to eil'ect an operation of said motor, and means operatively connected to said motor for rebalancing said bridge.

4. A telemetric system comprising. in combinetion, a transmitter including two transformers.

each having a primary winding and a pair 01' aiding secondary windings, means for energizing said primary windings, means for connecting said secondary windings in a closed loop, core members movable between the primary and secondary windings of each of said transformers, means tor positioning One of said core members in response to changes in a variable to be measured. means for reciprocating the other of said core members between limiting positions at least as far apart as the limiting positions of said first core memher, a circuit connected to a source of power and having a contactor normally assuming an open position, a phase sensitve device connected to said closed loop at diametrically opposite points operative at a predetermined phase for closcaid contactor, a receiver including a baleuceable bridge network, means operating when said circuit is energized to produce a condition to unbalance said bridge in one direcoperating when said circuit is deenerto produce a condition tending to unonce said bridge in the opposite direction, a

slbie motor, means operative on an unbalin a direction depending upon the direc- Ci. imbalance, means positioned by said '1' for rebaloncing said bridge. t emetric system comprising, on, on electric circuit, means for energizing said circuit intermittently for interva s of time with changes in a variable to be roses ured, a calen-ceacle circuit, means electrisally independent of the bridge tending to unbalance said bridge circuit in proportion to the length of the intervals durin which said circuit is energmed, a reversible motor, means responsive to the balance conditions 01 said bridge and opcrative on unbalance to efiect an operation oi said motor, and means positioned by said motor for rebalancing said bridge.

6. A telemetric system comprising, in combination, an electric circuit, means for energizing said circuit intermittently for intervals of time varying with changes in a variable to be measured, a balanceable bridge circuit, means operative in response to the energizing of said electric circuit for producing a condition tending to unbalance said bridge circuit in one direction, means operative when said electric circuit is deenergized for producing a condition tending to unbalance said bridge circuit in the opposite direction, a reversible motor, means responsive to the balance conditions of said bridge and operative on unbalance to effect an operation of said motor in a direction depending upon the direction of unbalance, and means positioned by said motor for rebalancing said bridge.

'i. A telemetric system comprising, in combination, an electric circuit, means for energizing said circuit intermittently for intervals 01 time varying with changes in a variable to be measured, a balanceable bridge circuit having resistance elements forming two of its legs and varying in resistance in response to changes in temperature, means operative on an energizing oi said'circuit for heating at least one of said resistance elements and operative at least on a deenergizing of said circuit for heating the other of said resistance elements, a reversible motor, means r sponsive to the balance conditions of said bridge and operative on unbalance to effect an operation of said motor in a direction depending upon the direction of unbalance,v and means positioned by said motor for rebalancing said bridge.

8. A telemetric system comprising, in combination, an electric circuit, means for energizing said circuit intermittently for intervals of time varying with changes in a variable to be measured, a balanceable bridge circuit having resistance elements forming @wo or its legs and varying in resistance in response to changes in temperature, means connected in said circuit and operative to eflect a heating of one of said resistance elements during intervals or time varying with the intervals the circuit is energized, adjustable means for heating the other of said resistance elements, and means operative on an unbalance 0! said bridge for adjusting said last mentioned means.

a. A teiemetric system comprising, in combination an electric circuit, means for transmitting signals over said circuit varying in response to changes in a condition to be measured, a balanceable bridge circuit having resistance elements forming two of its legs and varying in resistance in response to changes in temperature, heating elements for said resistance elements, means for subjecting one of said heating elements to a predetermined voltage during intervals of time varying with the signals transmitted, means for subjecting the other of said heating elements continuously to a voltage, said last mentioned means including an adjustable member for varying the voltage to which the element is subject, and means operative on unbalance of said bridge for adjusting said adjustable member.

10. A telemetric system comprising, in combination, an electric circuit, means for energizing said circuit intermittently for intervals of time varying with changes in a variable to be measured, a balanceable bridge circuit having resist ance elements forming two of its legs and varying in resistance in response to changes in temperature, heating elements for said resistance elements, a circuit for one of said heating elements connected to a source of constant voltage and having a contactor adapted to be closed in re sponse to the energizing of said first mentioned circuit, a circuit for the other or said heating elements and having adjustable means for subjecting it to a variable voltage, and means operative on an unbalance of said bridge for adjusting said adjustable means in a direction to return the bridge to a balanced condition.

ANTHONY J. HORNFECK.

REFERENCES CITED The following references are of record in the flleoi this patent:

UNITED STATE PATENTS Number Name Date 1,388,632 Dean Aug. 23, 1921 1,995,594 Wunsch Mar. 26, 1935 2,282,480 Keeler May 12, 1942 2,310,955 Hornfeck Feb. 16, 1943 2,371,415 Tolson Mar. 13, 1945 2,381,009 Siderman Aug. 7, 1945 2,398,341 Wills Apr. 9, 1946 2,400,170 Silverman May 14, 1946 2,403,917 Gille July 16. 1946 2,437,242 Cole et al. Mar. 9, 1948 2,439,891 Hornieck Apr. 20, 1948 2,440,189 Zworykln Apr. 20, 1948 2,441,226 Phillips May 11, 1948 

